Matrices · manipulative

A seal colony, year by year

Pups grow into older classes on a rocky beach. The Leslie matrix is the birth and survival rules that turn this year’s colony into next year’s.

Rocky islet · Southern Ocean
Year 0

Each stack is one year — colour mix shows age structure

Age classes

The story this year

Birth & survival rules (= Leslie matrix L)

start

Top row: pups born per older class · Subdiagonal: survival into the next age

Time

y0

Jump recomputes instantly (no 20-year animation). Next year still plays the three-act story.

In matrix form

Beach shows whole seals. The vector keeps decimals for next year.